Preliminary results of the CNBC Fed Survey for July show 70 percent of the 40 participants who responded believe Obama will pick Yellen, currently, the Fed's vice chair, to replace current Chairman Ben Bernanke, whose term is up in January.

Just 25 percent believe it will be the former Treasury Secretary Larry Summers.

(Read more: Battle of the sexes in choice for new Fed leader)

Yellen also beats Summers when CNBC asks participants who the president should nominate, with 50 percent choosing Yellen and 12.5 percent saying he should reappoint Bernanke. Even write-in candidate John Taylor, the Stanford University economist, beats out Summers on who the president should nominate.

Participants, who include economists, traders and strategists, say monetary policy expertise is the most important quality for a new Fed chairman.

Among the 10 qualities asked about, the ability to manage a financial crisis ranked second and good communications skills was third followed by respect from financial markets and concern about inflation.

Asked to judge the two supposed front-runners on these qualities, Yellen beat Summers in seven of 10 categories, including four of the top five.

In fact, Yellen got much higher grades from the Street on monetary policy expertise and concern about unemployment, which is a major issue for President Obama. Summers is seen having more respect from international leaders, greater concern about inflation and a higher level of financial market expertise.

Wall Street, however, doesn't think the next Fed chairman will be all that different from Ben Bernanke. Fifty-five percent said whomever is chosen will be neither more hawkish nor more dovish than Bernanke on monetary policy.

The complete results of this month's Fed Survey will be released Tuesday morning.

Here's what the Wall Street pros we surveyed said about who Obama should nominate to be Fed chief.

Who should Obama nominate for Fed chairman?

Janet Yellen

50.0%

Ben Bernanke

12.5%

John Taylor

12.5%

Glenn Hubbard

7.5%

Roger Ferguson

5.0%

Larry Summers

2.5%

Martin Feldstein

2.5%

Paul Volcker

2.5%

Steve Liesman

2.5%

Don't know/unsure

2.5%

Alan Krueger

0.0%

Christina Romer

0.0%

Source: CNBC Fed Survey

Correction: This story has been updated to reflect that John Taylor is an economist at Stanford University.

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